Kiss1 (kisspeptin gene)- and Gpr54 (kisspeptin receptor gene)-deficient mice, rats, and humans are infertile and associated with hypogonadotropic hypogonadism (De Roux et al., 2003; Seminara et al., 2003; Lapatto et al., 2007; Watanabe et al., 2014; Uenoyama et al., 2015, 2021; Tsukamura, 2022). Here, KISS1R is linked to hypogonadotropic hypogonadism.